Selling my 17-40 f/4L for 17-55 f/2.8 IS

Started May 21, 2012 | Discussions thread
ultimitsu Veteran Member • Posts: 6,650
Re: Selling my 17-40 f/4L for 17-55 f/2.8 IS

eorlingas wrote:

Hmm, I'm picking up my copy in a few days (already paid for it).

I realise you already paid for it... but if they allow it, you should try out sigma 17-50 OS. apparently this lens is almost as sharp overall, but has a better light transmission by about 0.3 stop and possibly a free hood, not to mention a lot cheap

Assuming that they let me open it up there and test it, how do I objectively measure whether it is sharp or not?

They are all sharp. lemons are very rare.

What happens often though, is that due to the manufacturing tolerance, a lens may be +2 and your camera maybe -2, togather they would have focus mis-alignment of 4, which becomes noticeable. luckily you have MFA, so you can correct it.

read the "myth about sharpness" article on lensrental to get a better understanding of this issue.

Did you just take random photos with the lens and see on the LCD???

take a focus chart and shoot it in the store, I did this.

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